Today, as vehicle interior materials or coverings of chairs, composite materials in which a skin material such as a knitted fabric, a woven fabric, a non-woven fabric, a synthetic leather, or an artificial leather and a flexible polyurethane foam sheet are laminated together are used. In order to improve the designability of the above-described composite materials, there are cases in which a bumpy design is formed on the surface. For example, in order to impart a bumpy design, composite material surfaces are embossed. However, flexible polyurethane foam sheets constituting composite materials are elastic. Therefore, even when composite materials are heated and pressed by means of embossing, in a case in which the design is a fine bumpy shape, there is a problem in that a sufficient shape-imparting effect cannot be obtained due to compression resilience attributed to the elasticity of flexible polyurethane foam sheets.
For example, PTL 1 discloses a method in which, in order to form a deep bumpy pattern, a skin material on which a thick flexible polyurethane foam is laminated is processed using an embossing device having a heat roll. However, this method cannot be said to be enough to satisfy both the depth of the bumpy pattern and the durability of cushioning performance.